Femtosecond LASIK combined with astigmatic keratotomy for the correction of refractive errors after penetrating keratoplasty

Post-penetrating keratoplasty astigmatism

Postoperative astigmatism is one of the common complications affecting visual outcomes after a penetrating keratoplasty. It can result from various factors related to host, donor and surgical technique, resulting in suboptimal visual outcome. While some of the measures taken during preoperative planning and during actual surgery can reduce the magnitude of postoperative astigmatism, postoperative correction of astigmatism is often required in cases with high degrees of astigmatism. When spectacles and contact lenses fail to provide optimal visual outcomes, various surgical techniques that include astigmatic keratotomy, compression sutures, toric intraocular lens placement, and laser refractive procedures can be considered. When none of these techniques are able to achieve a desired result with in the acceptable optical range, a repeat keratoplasty is considered a last option. We discuss the various causes and management of complication of postoperative astigmatism occurring after a full thickness corneal transplantation surgery.

Video recording and light intensity change analysis during cataract surgery using an animal model

PURPOSE

To estimate light exposure changes during cataract surgery through intraoperative images simulated from the "patient's perspective" using an animal model.

METHODS

In this experimental study, a 3-mm maculostomy was performed through the posterior globe's surface of 15 porcine eyes. Eyes were fixated to a glass slide and placed over an iPad camera. Video footage of a cataract surgery was obtained through the maculostomy for each eye, keeping light exposure parameters and focus constant. Seventy-five images, five from each eye, were extracted at pre-determined points, and mean gray value (MGV), a light intensity measure, was calculated. Differences in MGV between discrete surgical steps were evaluated using multiple one-sample t-tests.

RESULTS

This technique allowed for the capture of a full-length cataract surgery through a 3-mm maculostomy. MGV range was 14.21-132.51. Light intensity was similar across surgeries and varied greatly through each procedure. A 24% decrease in MGV between post-hydrodissection and post-phacoemulsification stages was noted (difference - 18.36; 95% CI - 30.50 to - 6.22; p value = 0.006). A 22.4% decrease in light intensity was noted after phacoemulsification in comparison to the starting image (MGV difference - 16.78; 95% CI - 32.45 to - 1.12; p value: 0.0375). Light intensity was similar at the start and end of surgery (difference - 7.15; 95% CI - 19.35 to + 5.05; p value = 0.229).

CONCLUSIONS

Light intensity changes through different steps of cataract surgery and may be minimal after phacoemulsification completion. This video and data may serve as informational and educational tools for surgeons and patients.

Deep Intrastromal Arcuate Keratotomy With In Situ Keratomileusis (DIAKIK) for the Treatment of High Astigmatism After Keratoplasty: 2-Year Follow-up

PURPOSE

To describe 2-year results of deep intrastromal arcuate keratotomy with in situ keratomileusis (DIAKIK) for the treatment of high astigmatism after keratoplasty.

METHODS

This prospective study included 20 eyes from 20 patients presenting with high astigmatism after keratoplasty. All were treated by two-step femtosecond laser surgery, with two intrastromal arcuate keratotomies and a corneal flap, followed a few months later by excimer photoablation after reopening of the flap.

RESULTS

At 24 months, both uncorrected (UDVA) and corrected (CDVA) distance visual acuity had improved from 1.12 ± 0.42 logMAR (20/200 Snellen) before surgery to 0.58 ± 0.23 logMAR (20/80 Snellen) (P < .001) and from 0.31 ± 0.26 logMAR (20/40 Snellen) to 0.20 ± 0.20 logMAR (20/32 Snellen) (P = .04), respectively. The mean spherical equivalent improved from -5.01 ± 4.35 to -1.54 ± 2.42 diopters. The mean efficacy index was 0.63. The mean correction index was 0.93 ± 0.32. The mean flattening index was 1.09 ± 0.75 and the mean safety index was 1.39. No graft rejection or epithelial ingrowth was observed.

CONCLUSIONS

This two-step procedure was an effective treatment for high astigmatism after keratoplasty. The use of both femtosecond and excimer lasers helped to avoid some complications that would have jeopardized the grafts. Refractive and topographic stability was good 2 years after surgery. [J Refract Surg. 2019;35(4):239-246.].

Combined intrastromal astigmatic keratotomy and laser in situ keratomileusis flap followed by photoablation to correct post-penetrating keratoplasty ametropia and high astigmatism: One-year follow-up

PURPOSE

To evaluate a new technique combining intrastromal astigmatic keratotomy (AK) with a laser in situ keratomileusis (LASIK) flap followed by excimer laser photoablation to correct post-penetrating keratoplasty (PKP) high astigmatism and ametropia.

SETTING

Kasr El Aini Hospital, Cairo University, Cairo, Egypt.

DESIGN

Prospective interventional uncontrolled case series.

METHODS

Patients with post-PKP high astigmatism and ametropia had paired intrastromal AK with LASIK flap using the M2 microkeratome followed 2 to 3 months later by excimer laser photoablation. The main outcome measures were uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), mean refractive spherical equivalent (SE), and mean cylinder after each step and at the 1-year follow-up.

RESULTS

The study comprised 20 eyes (20 patients). All parameters were significantly improved in all patients by the last follow-up visit. The mean UDVA improved from 1.07 logMAR ± 0.2 (SD) preoperatively to 0.23 ± 0.18 logMAR (P < .001), the mean CDVA improved from 0.79 ± 0.18 logMAR to 0.12 ± 0.12 logMAR (P < .001), the mean refractive SE improved from -5.04 ± 2.62 diopters (D) to -1.47 ± 1.32 D (P = .001), and the mean cylinder reduced from -5.39 ± 0.98 D to -1.05 ± 0.71 D (P < .001). The mean correction index was 0.84 ± 0.10, and the mean flattening index was 0.83 ± 0.10. Thirty-five percent of cases developed microperforations, and 15% developed epithelial ingrowth.

CONCLUSION

This combined approach allowed for the correction of high astigmatism and ametropia following PKP; however, epithelial ingrowth requiring intervention is a complication to be considered.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.

New combined technique of deep intrastromal arcuate keratotomy overlayed by LASIK flap for treatment of high astigmatism

PURPOSE

The aim of this study was to describe a novel technique combining deep intrastromal arcuate keratotomy and superficial lamellar keratotomy followed by excimer photoablation for the management of high naturally occurring or postkeratoplasty astigmatism.

METHODS

In this retrospective case series, the first step was deep intrastromal arcuate keratotomy and superficial lamellar keratotomy performed at 100-μm depth by femtosecond laser. Manual incisions were made for flap elevation. The second step, after 1 month, consisted of reopening the flap and using an excimer laser to correct residual ametropia.

RESULTS

Nine eyes series were studied. The mean preoperative refractive cylinder correction was 6.11 ± 2.54 diopters (D). The mean postoperative refractive cylinder correction was 2.85 ± 1.31 D. The mean correction index was 1.07 ± 0.28 D. The mean best-corrected visual acuity improved from 20/40 to 20/22 after the 2 steps. The median follow-up was 11 (range, 9-17) months. No complications were observed and postoperative outcome was satisfactory.

CONCLUSIONS

Permitting correction of a broader range of high astigmatism with good accuracy, this combined approach minimizes excision of corneal stromal tissue and postoperative complications.

Laser in situ keratomileusis in 2012: a review

Laser in situ keratomileusis (LASIK) is a safe and effective treatment for refractive error. A combination of technological advances and increasing surgeon experience has served to further refine refractive outcomes and reduce complication rates. In this article, we review LASIK as it stands in late 2012: the procedure, indications, technology, complications and refractive outcomes.

Beveled femtosecond laser astigmatic keratotomy for the treatment of high astigmatism post-penetrating keratoplasty

PURPOSE

To use beveled femtosecond laser astigmatic keratotomy (FLAK) incisions to treat high astigmatism after penetrating keratoplasty.

METHODS

Paired FLAK incisions at a bevel angle of 135 degrees, 65% to 75% depth, and arc lengths of 60 to 90 degrees were performed using a femtosecond laser. One case of perpendicular FLAK was presented for comparison. Vector analysis was used to calculate the changes in astigmatism. Fourier domain optical coherence tomography was used to examine incision morphology.

RESULTS

Wound gaping requiring suturing was observed in the case of perpendicular FLAK. Six consecutive cases of beveled FLAK were analyzed. Fourier domain optical coherence tomography showed that beveled FLAK caused a mean forward shift of Bowman layer anterior to the incisions of 126 ± 38 μm, with no wound gaping. The mean magnitude of preoperative keratometric astigmatism was 9.8 ± 2.9 diopters (D), and postoperatively it was 4.5 ± 3.2 D (P < 0.05). Uncorrected visual acuity improved from 1.24 ± 0.13 logarithm of the minimum angle of resolution preoperatively to 0.76 ± 0.38 postoperatively (P < 0.05). Best spectacle-corrected visual acuity improved from 0.43 ± 0.33 logarithm of the minimum angle of resolution preoperatively to 0.27 ± 0.24 postoperatively (P = 0.22). Visual results were reduced in 2 patients by cataract progression. Between 1 and 3 months after beveled FLAK, the keratometric cylinder was stable (<1 D change) in 5 of 6 patients, and regressed in 1 patient. No complications occurred.

CONCLUSIONS

Beveled FLAK incisions at varied depth are effective in the management of postkeratoplasty astigmatism. Early postoperative changes stabilized within 1 month in most patients. Further studies are needed to assess long-term outcomes.